The invention discloses an automatic-feeding and uniform-discharging cement mixer with a conveying belt. The automatic-feeding and uniform-discharging cement mixer comprises a bottom sand-gravel tank, a conveying motor, a side protection plate, the conveying belt, transmission rollers, riding wheels and screw blades. A front mixing tank support and a rear mixing tank support are arranged on the right side of a base plate, the riding wheels are mounted on the front mixing tank support and the rear mixing tank support respectively, and a mixing tank is placed on the riding wheels. The left side of the mixing tank is provided with a feeding inlet, the right side of the mixing tank is provided with a discharging outlet, and a gear ring is arranged in the middle of the mixing tank. One end of the side protection plate is fixed onto the bottom sand-gravel tank, and the other side of the side protection plate is arranged in the feeding inlet. Two transmission shafts are arranged on the side protection plate. The transmission rollers are arranged on the transmission shafts which are connected with the conveying motor. The conveying belt is mounted on the transmission rollers. The automatic-feeding and uniform-discharging cement mixer has the advantages that uniform discharging is achieved, cement waste is reduced, labor intensity of workers is relieved greatly, and the cement mixer formed by different modules is simple in structure and convenient to transport.